638711231 has 4 divisors (see below), whose sum is σ = 639562464. Its totient is φ = 637860000.

The previous prime is 638711221. The next prime is 638711251. The reversal of 638711231 is 132117836.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 638711231 - 2¹⁸ = 638449087 is a prime.

It is a super-2 number, since 2×638711231² = 815904073211070722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638711221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 424490 + ... + 425991.

It is an arithmetic number, because the mean of its divisors is an integer number (159890616).

Almost surely, 2^638711231 is an apocalyptic number.

638711231 is a deficient number, since it is larger than the sum of its proper divisors (851233).

638711231 is an equidigital number, since it uses as much as digits as its factorization.

638711231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851232.

The product of its digits is 6048, while the sum is 32.

The square root of 638711231 is about 25272.7369115417. The cubic root of 638711231 is about 861.1950355011.

The spelling of 638711231 in words is "six hundred thirty-eight million, seven hundred eleven thousand, two hundred thirty-one".